1. Field of the Invention
The present invention relates to compositions and methods for treating hair in which a cosmetically acceptable medium is used which contains from 0.1-10% by weight of an ampholyte terpolymer. In particular, the cosmetically acceptable medium is an anionic surfactant-containing shampoo, and the ampholyte terpolymer exhibits good compatibility therewith in that the final solution is clear.
The surface properties of human hair are, of course, of basic interest in cosmetic science, and there has thus been a long-standing desire to discover ingredients which will beneficially affect the topical and bulk condition of this keratinous substrate. Such ingredients must have adequate adherent properties, so that they are not only adsorbed initially, but are also retained on exposure to water. This property is referred to as "substantivity", i.e., the ability of a material to be adsorbed onto the keratin of the hair and to resist removal by water rinse-off.
As indicated, human hair is composed of keratin, a sulfur-containing fibrous protein. The isoelectric point of keratin, and thus of the hair of which it is composed, is in the pH range of 3.2-4. Thus, at the pH of typical shampoo conditions, hair carries a net negative charge. Consequently, cationic polymers have long been used as conditioners in shampoo formulations, or as a separate treatment, in order to improve the wet and dry combability of the hair. The substantivity of the cationic polymers for negatively charged hair leads to film formation that facilitates detangling in wet hair combing and a reduction in static flyaway in dry hair combing. The cationic polymers also impart softness and suppleness to the hair.
It is a feature of the ampholyte terpolymers of the present invention that by varying the molar amounts and/or types of cationic components of the overall terpolymer, it is possible to adjust the cationic nature of the amphoteric polymer. By altering the mole percent charge, distribution of the cationic charge on the polymer backbone, and distance from the backbone (side chain length), one can achieve variations in the substantivity, conditioning properties, and static flyaway control of the resulting ampholyte terpolymer.
When cationic polymers are added to shampoos containing anionic surfactants, formation of highly surface active association complexes takes place which imparts improved foam stability to the shampoo. Maximum surface activity and foam stability, or lather, are achieved at near stoichiometric ratios of anionic sufactant:cationic polymer, where the complex is least water soluble. All cationic conditioners exhibit some incompatibility at some of these ratios. Compatibility gives a commercially more desirable clear formulation, while incompatibility leads to a haze or precipitation, which is aesthetically less desirable.
Hair fixative properties such as curl retention, are directly related to the film forming properties of the cationic monomers, as well as to molecular weight, with performance increasing with increasing molecular weight. However, the fixative properties conferred by the cationic monomers tend to have a reciprocal relationship to the other conditioning properties, i.e., good curl retention means that wet combability, for example, will suffer, and vice versa.
Nevertheless, the ampholyte terpolymers of the present invention give one the ability, by varying the proportions and individual character of the nonionic, cationic and anionic components, to balance the hydrophobic and hydrophilic characteristics of the overall ampholyte terpolymer, thereby permitting one to optimize the conditioning properties or fixative properties, or a mixture of both.
It is also possible, by varying the types and proportions of the nonionic, cationic and anionic components, especially the anionic components, of the ampholyte terpolymers of the present invention, to be able to adjust the acidic nature, e.g., the pK.sub.a, of the anionic component of those terpolymers so as to more closely adjust the intrapolymer and polymer/hair interactions, and thereby favorably affect the resulting conditioning and fixative properties.
Surprisingly, it has been found that it is possible, by adjusting the weight proportions and types of the components of the ampholyte terpolymers of the present invention, to retain a desired balance of the beneficial conditioning properties conferred by each of those components. Thus, it is possible to keep the desired properties of substantivity, combability and feel, while at the same time improving anionic surfactant compatibility, curl retention, sheen, and static reduction properties. It is also possible to selectively optimize one or a subset of these conditoning properties, by proper proportioning of the components and their molecular weights. This may be a desired course of action responsive to an expression of consumer group preference for one or another of these various conditioning properties, depending on the makeup of that consumer group.
As already indicated, it is a preferred embodiment of the present invention to add the ampholyte terpolymers directly to an anionic surfactant-containing shampoo. Other embodiments are contemplated, however. Thus, excellent results have been achieved with treatments usually followed by rinsing, such as shampooing, but have also been achieved with treatments with lotions or creams followed by rinsing, which are used to obtain hair-conditioning effects and are applied before or after coloring, bleaching, shampooing, perming or straightening.
Thus, the compositions according to the present invention can also be used in the form of coloring products, setting lotions, blow-drying lotions, restructuring lotions or bleaching, perming or straightening products.
2. Brief Description of the Prior Art
Heretofore, hair conditioning additives have been largely of three different types: cationic polymers, proteins or protein derivatives, and fatty quaternary ammonium compounds. Commonly used cationic polymers include: quaternary nitrogen-containing hydroxyethyl cellulose compounds, copolymers of vinylpyrrolidone and dimethylaminoethylmethacrylate, and amino functional polydimethylsiloxane. Hydrolyzed animal protein has been frequently used as a hair conditioner. Also used are natural products such as collagen and casein. Suitable quaternary ammonium compounds include such products as stearyl dimethyl ammonium chloride.
Conditioning additives comprising copolymers of dimethyldiallylammonium chloride and other monomers are well known; see, e.g., EP 308189 (with acrylamide); EP 0 308 190 and U.S. Pat. No. 4,803,071 (with hydroxyethyl cellulose). The use of such polymers in cosmetics is also described in Sykes et al., Drug Cosmet. Ind., 126(2), 62, 64, 66, 68, 136 (1980). Amphoteric betaines have also been employed in cosmetic compositions; see GB 2,113,245 which discloses use of betainized dialkylaminoalkyl(meth)acrylate together with a cationic polymer.
The use of polymers of dimethyldiallylammonium chloride alone in hair treatment compositions is also known. See, e.g., U.S. Pat. Nos. 4,175,572 and 3,986,825.
While the use of various combinations of cationic, anionic and/or nonionic polymers as additives for hair conditioning compositions has been suggested heretofore, there has been no appreciation that a significant improvement in all of the desired hair conditioning properties could be obtained by employing an ampholyte terpolymer of the type used in the compositions and methods of the present invention.
For example, U.S. Pat. No. 4,859,458 discloses hair conditioning polymers containing alkoxylated nitrogen salts of sulfonic acid which may also include additional monomers that may be neutral, anionic and/or cationic. While these include acrylamide, acrylic acid and dimethyldiallylammonium chloride, there is no suggestion of the ampholyte terpolymers of the present invention.
EP 0 353 987 discloses polymers for water-rinsable personal care products including conditioning shampoos, comprising a cationic monomer including dimethyldiallylammonium chloride, a monomer that carries a pendant group A.sub.n R where n is 0 or a positive integer, A is ethyleneoxy and R is a hydrocarbyl group of 8 to 30 carbon atoms, and optionally a nonionic and/or an anionic monomer. However, there is no suggestion of the ampholyte terpolymers of the present invention.
U.S. Pat. No. 4,710,374 discloses compositions suitable for treating the hair comprising a cationic polymer including poly(dimethyldiallylammonium chloride), and an anionic latex, but there is no suggestion of the ampholyte terpolymers of the present invention.
U.S. Pat. No. 4,842,849 discloses compositions suitable for treating the hair comprising at least one cationic polymer including poly(dimethyldiallylammonium chloride), and at least one anionic polymer containing vinylsulfonic groups, optionally copolymerized with acrylamide. The cationic polymer may be an amphoteric polymer as defined, but none of these combinations suggest the ampholyte terpolymers of the present invention.
EP 0 080 976 discloses aqueous hair-cosmetic compositions containing a surface active polymeric acrylic-based quaternary ammonium salt, a monomeric or oligomeric ammonium salt, and a surface active nonionic, anionic or zwitterionic component. The ampholyte terpolymers of the present invention are not suggested.
The ampholyte terpolymers of the present invention are regarded as novel compositions of matter because of their unique properties, and their use as hair conditioning additives has not heretofore been suggested.
Terpolymers of acrylamide/dimethyldiallylammonium chloride/acrylic acid are disclosed in U.S. Pat. Nos. 4,455,240; 4,460,477; 4,484,631; and 4,533,708; however, nowhere is there a suggestion that those terpolymers might be used as conditioning additives for hair products.
A graft copolymer of acrylamide/acrylic acid/amylopectin/dimethyldiallylammonium chloride is disclosed in U.S. Pat. No. 4,131,576, but is only suggested for use as a pigment retention agent in papermaking.
The ampholyte terpolymers of the present invention represent a significant advance in the state of the hair conditioning art and afford properties which are a surprising improvement over those possessed by the hair conditioning additives in the prior art described above. In contrast to such additives, the ampholyte terpolymers of the present invention provide either an optimized combination of all hair conditioning properties, or else an optimized subset of such properties, which include: detangling, wet combability, wet feel, dry combability, dry feel, sheen, static flyaway control, and curl retention. A detailed demonstration of the dramatic improvement in these properties is set out further below.